This invention relates to a molded pulp product and apparatus and method for producing the same.
Molded pulp products have heretofore been produced including fine pulp products. Such fine pulp products have been produced in a press-to-dry procedure by progressively stepping a wet pulp part under pressure through a plurality of heated tools. The molded pulp product produced in such a procedure because of the pressure applied has a relatively smooth surface on one side which is smoother than the other. It has been found that such fine pulp products because they are made in this manner have an unnatural laying down of the fibers to create striations that appear like laminations which has been found to decrease the strength of a fine molded product and also to increase its brittleness. Such fine molded products also have surfaces which are rougher than the other surfaces and thus have unpredictable variable stacking pitches which affect the nesting and denesting capabilities. This differing roughnesses of the surfaces and the variable stacking pitches also make it difficult to de-nest the fine molded products. There is therefore a need for a new and improved molded pulp product which does not have these undesirable features and also a new and improved apparatus and method for producing the same.
In general, it is an object of the present invention to provide a molded pulp product having improved characteristics and an apparatus and method for producing the same.
Another object of the invention is to provide a molded pulp product which can be created with much tighter tolerances.
Another object of the invention is to provide a molded pulp product which has a predictable stacking pitch.
Another object of the invention is to provide a molded pulp product of the above character in which the stacking pitch can be reduced.
Another object of the invention is to provide a molded pulp product of the above character in which first and second surfaces of the molded product have opposing surfaces which are relatively smooth.
Another object of the invention is to provide a molded pulp product of the above character utilized from first and second mating molds having screens and in which the first and second surfaces emulate the screen patterns of the screens of the first and second molds.
Another object of the invention is to provide a molded product of the above character in which the surfaces of both sides are precisely controlled.
Another object of the invention is to provide an apparatus and method of the above character in which the mold is carried by a platen and in which the mold is introduced into the fiber slurry in an upside down positions and with the platen remaining dry.
Another object of the invention is to provide an apparatus and method of the above character after the wet molded product has been formed on the tool in which the platen and the mold are inverted to a right-side up position so that the platen underlies the mold.
Another object of the invention is to provide an apparatus and method of the above character which facilitates the drainage of water from the wet molded product carried by the mold.
Another object of the invention is to provide an apparatus and method of the above character in which the mold carrying the wet molded product is advanced into a heated atmosphere.
Another object of the invention is to provide an apparatus and method of the above character in which the mold is advanced into a mating mold in the drying chamber so that mold impressions are formed on first and second surfaces of the molded pulp product.
Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings.